Multiple-Streams Focusing-Based Cell Separation in High Viscoelasticity Flow

Viscoelastic flow has been widely used in microfluidic
particle
separation processes, in which particles get focused on the channel
center in diluted viscoelastic flow. In this paper, the transition
from single-stream focusing to multiple-streams focusing (MSF) in
high viscoelastic flow is observed, which is applied for cell separation
processes. Particle focusing stream bifurcation is caused by the balance
between elastic force and viscoelastic secondary flow drag force.
The influence of cell physical properties, such as cell dimension,
shape, and deformability, on the formation of multiple-streams focusing
is studied in detail. Particle separation is realized utilizing different
separation criteria. The size-based separation of red (RBC) and white
(WBC) blood cells is demonstrated in which cells get focused in different
streams based on their dimension difference. Cells with different
deformabilities get stretched in the viscoelastic flow, leading to
the change of focusing streams, and this property is harnessed to
separate red blood cells infected with the malaria parasite, Plasmodium falciparum. The achieved results promote
our understanding of particle movement in the high viscoelastic flow
and enable new particle manipulation and separation processes for
sample treatment in biofluids.